Internal, undesired arcs generated within cathode ray tubes (CRT) have long been a problem. As voltage differentials between the electrodes have increased, as for example in modern color CRT's where differentials of 30 KV exist, this problem has become magnified.
Among the most commonly suggested solutions to this problem has been the use of interior conductive coatings having a high electrical resistance to replace the previously employed coatings which were substantially graphite. To achieve the arc limiting capabilities of these high electrical resistance coatings however, it has been necessary to modify either the antenna getter structure or to change the location of the getter so as to avoid the creation of a highly conductive path to the electron gun.
For example, German Offenlegungsschrift No. 2652277 discloses an isolation technique including an insulator between the getter and the convergence cage, a complicated and expensive structure.
U.S. Pat. No. 2,159,946 discloses mounting the getters about the funnel portion of a picture tube, again, a complicated and expensive solution where color picture tubes are concerned because of the difficulty in placing the getters.
U.S. Pat. No. 3,961,221 discloses a wheelbarrow getter arrangement wherein the "wheel" can be formed of an insulating material, such as ceramic. While this device works well in theory, in practice it has been found necessary to keep sublimed getter materials from building up upon the wheel, which causes leakage paths, thus ineffectuating the device.
Yet another technique has involved mounting the getter upon the shadow mask of a color CRT. This solution is shown in U.S. Pat. No. 3,979,633 and 3,979,806. This procedure is also expensive and time consuming, requiring additional operator manipulation.